The Pyramid is an arena in Memphis, Tennessee. It’s height is 321 ft., and it’s slant height is 436.5 ft. Find the length of the edge of the square base. Round the answer to the nearest tenth

1 answer

To find the length of the edge of the square base of the Pyramid, we can use the Pythagorean theorem. The pyramid forms a right triangle when we draw a line from the apex (top) of the pyramid to the center of the base and then down to one of the corners of the base.

Let:

  • \( h \) be the height of the pyramid (321 ft),
  • \( l \) be the slant height of the pyramid (436.5 ft),
  • \( a \) be the length of one edge of the square base, and
  • \( \frac{a}{2} \) be the distance from the center of the base to one of its corners.

Using the Pythagorean theorem:

\[ l^2 = h^2 + \left(\frac{a}{2}\right)^2 \]

Substituting in the known values:

\[ (436.5)^2 = (321)^2 + \left(\frac{a}{2}\right)^2 \]

Calculating \( (436.5)^2 \) and \( (321)^2 \):

\[ 436.5^2 = 190,372.25 \] \[ 321^2 = 103,041 \]

Now, substituting these values into the equation:

\[ 190,372.25 = 103,041 + \left(\frac{a}{2}\right)^2 \]

Subtract \( 103,041 \) from both sides:

\[ 190,372.25 - 103,041 = \left(\frac{a}{2}\right)^2 \] \[ 87,331.25 = \left(\frac{a}{2}\right)^2 \]

Taking the square root of both sides to find \( \frac{a}{2} \):

\[ \frac{a}{2} = \sqrt{87,331.25} \] \[ \frac{a}{2} ≈ 295.5 \]

Now, we multiply by 2 to find \( a \):

\[ a ≈ 2 \times 295.5 ≈ 591.0 \]

Thus, the length of the edge of the square base is approximately 591.0 ft.